This invention relates to a sight system, and, more particularly, to an improved sighting system for use on a craft wherein a movable member mounted on the craft is slaved to a relatively freely movable sight device so that the axis of the movable member is parallel to the axis of the sighting device.
There are instances in which it is desired to be able to position a member mounted on a movable craft on, or relative to, a line of sight orientation with respect to some remote point. Typical such instances are pointing an aircraft mounted armament at another aircraft or at a point on the ground; pointing a photographic or television camera at such a "target"; pointing a spotlight or other member, e.g., infrared sensor, radar antenna and the like. Some such devices are on a true line of sight orientation while others may be on a ballistic line of sight, i.e., compensated for wind, drift, etc. Where the member is fixedly mounted with respect to the craft, the pilot achieves a "line of sight" to the target by maneuvering the craft in a line of sight orientation with respect to the target. In many instances, however, the craft mounted member is movable independently of the craft and under the control of a crew member not necessarily the pilot. In such a case, the slaving of the independently movable member, controlled by a crew member, on a line of sight orientation to a target, which may be a fixed or movable point, presents some unique problems especially for bulky items.
Where the craft on which the member is mounted is a highly maneuverable craft, such as a helicopter, further complications arise especially if the tracking mission is carried out in a hostile environment. For example, if a helicopter is used in a firing mission in which a high rate of fire type of weapon is used to sweep a zone of fire, the craft might take evasive action by a maneuver which is not the optimum to achieve effective results in the firing mission. In such an instance the crew member must be capable of directing the fire accurately at the intended target area, even though the pilot is engaged in evasive maneuvers. Essentially the same conditions exist in the case of a photographic tracking mission or other types of missions in a hostile environment.
As will be appreciated, the armament, for example, is mounted on the craft for movement in azimuth and elevation relative to the aircraft, essentially x-y directions. The aircraft is movable in a pitch, azimuth and roll direction, i.e., x-y and z directions. The crew member, under these circumstances attempts to direct the orientation of the armament, camera or the like on a "line of sight" position to a point on the ground or elsewhere even though the craft is maneuvering and thus also moving the member mounted on the craft.
As will be appreciated, the provision of an efficient system, which is reliable and accurate, while being light weight and relatively simple mechanically and which will achieve a slaving of the craft mounted member to a "line of sight" position, has distinct advantages. To accomplish this objective by a free sight system, i.e., one which is hand held and small while being easy to move, and which is not connected to some other unit by mechanical linkages also provides unique advantages.